In prior disk brakes of the type referred to, there is a tendancy for the brake disk to overheat upon the application of a braking force thereto, with the consequential disadvantages of loss or fading of braking power, and, buckling of the brake disk under the influence of the stresses thermally induced therein. In order to assist in the rapid dissipation of heat from the brake disk, it has heretofore been considered necessary to construct the disk brake in such a manner that the brake disk is exposed to air flow past the motor vehicle. Such a construction, however, carries with it the disadvantage that the brake disk is exposed to the elements and is subjected to fouling by water, mud, oil slick or the like, which again can seriously affect the braking capability of the brake, and further results in rapid attrition of the brake pads and scoring of the brake disk.